Nonreaowe connection for pulsation



March 24, 1964 E. J. HALTER 3,126,032

NONREACTIVE CONNECTION FOR PULSATION ABSORBER Filed Nov. 14, 1963000000000 OOOOOQOOOO 0000 IN VENTOR.

United States Patent 3 126,032 NQNREACTIVE coNNnc'rroN FOR PULsATIoNAnsoanaa Edmund .l. Halter, Irving, Tern, assignor to Burgess-Manningr'jompany, Dallas, Tex" a corporation of Illinois Filed Oct. 14, 1963,Ser. N 315,965 2 Claims. (til. 138-26) This invention relates to devicesfor absorbing or damping the pulsations in pulsating flowing gases, suchas the intake or discharge of a reciprocating compressor. Moreparitcularly, the invention is directed to improved means for connectingpulsation absorbers with apparatus such as reciprocating compressorswhich tend to generate the pulsations in the flowing gas stream.

Various types of apparatus have been devised and are in use for thepurpose of attenuating the pulsations in gases flowing, for example,from a reciprocating compressor, the pulsations being caused by theintermittent introduction of the gas into the piping system from thedischarge valves or" the compressor. Attenuation of such pulsations isdesirable to prevent damaging vibration of the piping system, noise,erroneous meter readings, inter ference with gases being discharged fromthe compressor cylinders and other undesirable consequences of pulsatingflow. In general, pulsation absorbers, or snubbers or pulsationdampeners, as such apparatus is sometimes called, comprise means formingchambers which may contain impedance or other flow modifying structureswhich operate to smooth the flow of the gases and conduct the same tothe piping system.

For optimum performance, and especially for maximum value to theefliciency of the compressor or other apparatus to which the pulsationabsorbers are connected, it is desirable that the functioning pulsationabsorbing structure be connected as close as possible to the compressorports and thus to the compressor valves which, of course, are located atthe cylinder ports. Due to the relatively large size of the pulsationabsorber units and because of the necessity of providing access to thecompressor valves, the pulsation absorber units, themselves, mustnecessarily be spaced an appreciable distance from the compressor andconnection made by means of piping. Although relatively short, the pipeconnections between the compressor ports and the pulsation absorberpermit or cause undesirable build-up and reflection of pulsations. Inaddition to vibrations in these pipes at natural resonant frequenciesand harmonics thereof excited by the pulsations, the sudden change incross section of the connecting pipe as it opens into the interior ofthe pulsation absorber chamber causes reflection of pulsations backtoward the compressor.

The primary object of the invention is to eliminate, or at leastminimize, these undesirable vibrational consequences of theconventionally used connecting pipes between the compressor and likeapparatus and the pulsation absorbers. A related object is to enhancethe operation of the pulsation absorber by providing means for acting onthe pulsating gases immediately beyond the compressor ports, that is,between the compressor and the pulsation absorber.

The invention is described in greater detail in conjunction with theaccompanying drawings wherein:

FIG. 1 is a side view of a pulsation absorber having three compressorconnections, each embodying the invention, and

FIG. 2 is a cross-sectional view taken at the line 22 of FIG. 1.

In the interest of clarity, the acoustically nonreactive pulsationabsorber connection will be described as applicable to a pulsationabsorber unit arranged to receive the pulsating discharge from a threecylinder reciprocating compressor.

A typical pulsation absorber unit is illustrated in FIG. 1. Acylindrical shell 1 is closed at both ends by end headers 2. Threeintake connections 3 are provided in the cylindrical shell of the unitto make connection by means of flanges 4 with the three discharge portsof a compressor. A single pulsation aborber outlet connection 5 isprovided for connection of the absorber unit with the downstream pipingsystem. Thus, the pulsation absorber is interposed between the dischargeof the compressor and the piping system into which the compressed gasesare conducted for such use as may be made of them.

The internal construction of the pulsation absorber unit is not shown indetail since it is Well known and forms no part of the invention hereindescribed and claimed. It may be stated that the pulsation .absorberunit is divided into three snubbing sections by means of transverseheaders such as header 6 shown in FIG. 2. Perforated snubber impedancetubes 7a pass through the header and provide for the conduction of thegases to the absorber outlet 5.

The invention herein is specifically directed to the construction ofconnections 3 of the absorber with the compressor or otherpulsation-generating apparatus. As is shown in detail in FIG. 2, conduitmeans are provided for conduction of the gases entering the connectorsat flanges 4 into the interior of the absorber without reduction of thecross-sectional area of the conduit. This conduit comprises an internalperforated tube 7 and a concentric outer pipe 8 which is larger indiameter than the perforated tube to provide an expansion space 9between the perforated tube 7 and the outer pipe 8. Tube 7 issubstantially an extension of the opening in flange 4 and is perforatedthroughout its length for reasons hereinafter explained. The inner endof this tube may be flared, as at it if desired, but this is notessential.

Pipe 8 is heavy gauge and is securely welded to the shell 1 of thepulsation absorber unit, a collar 11 being supplied for additionalstrength inasmuch as the intake (in the case of a discharge snubber)connections 3 also serve to support the pulsation absorber when it hasbeen mounted upon the compressor. In the particular embodiment of theinvention illustrated in the drawing, the pipe section 8 is in the formof a swage nozzle having a uniform diameter throughout the part of itslength adjacent the pulsation absorber and necked down at the end weldedto flange 4 to match the internal diameter of the opening through theflange. This provides an increasing diameter with a resulting chamber 9which opens into the interior of the pulsation absorber.

For the purposes of the invention, it is important that the expansionspace 9 with its perforated interior Wall be brought as close as ismechanically possible to the connecting flange 4 and thus to thecompressor cylinder. Otherwise stated, it is desirable to minimize thelength of the passageway from the compressor to the perforated tube '7since this passageway, if of substantial length, acts acoustically as anopen ended tube with undesirable acoustical and vibrational influence asabove described. The perforated tube 7, on the contrary, is anacoustically nonreactive element since the gases are not fully confinedtherein as they flow through this tube into the pulsation absorber. Inaddition to the avoidance of the undesirable acoustical reactance of asolid connector tube, the combination of perforated tube and surroundingchamber 9 which opens into the interior of the pulsation absorbing unitpositively contributes to the damping of the pulations by permittingpreliminary expansion of the gasses as they pass through the intakeconnectors. Thus, by means of the invention, the disadvantages of thepulsation absorber intake connector elements heretofore employed havebeen eliminated and useful pulsation absorbing elements have beensubstituted in their stead.

While the dimensions of the elements of the pulsation absorberconnecting structure are not closely critical,

satisfactory results depend upon the acoustic and impedance eifect ofperforated tube 7 and the provision of adequate space 9. As a specificexample of a satisfactory structure for a typical application, the innertube '7 is 12 inches in diameter and 2 feet, 6 inches long and isuniformly perforated with 43 one inch diameter holes. The diameter ofthe swage nozzle 8 is 18 inches, reduced to 12 inches at the connectionend.

While the essential concepts of the invention have been disclosed anddescribed by means of the specific embodiment shown in the drawing, itwill be understood that specifically diiferent structural designs may beemployed without departing from the principles of the invention asdefined by the appended claims.

Invention is claimed as follows:

1. Means for connecting a pulsation absorber with a port of apulsation-generating apparatus such as a reciproeating compresser,comprising an outer pipe (8) having a reduced diameter at one endthereof and being rigidly fastened to and opening into the interior ofthe pulsation absorber at the other end' thereof, a perforated innertube (7) having substantially the same diameter as the reduced diameterof said outer pipe and extending through said pipe coaxially therewithand into the interior of the pulsation absorber, said inner tube andouter pipe defining an expansion space (9) therebetween, and meansadapted to proximately connect the reduced end of said pipe with a portof a pulsati0n-generating apparatus.

2. Structure in accordance with claim 1 wherein the outer pipe is aswage nozzle the diameter of which increases relatively gradually fromthat at the reduced end to a diameter which obtains throughout thegreater part of the length of the pipe.

References Cited in the file of this patent UNITED STATES PATENTS696,277 Sponseller et al Mar. 25, 1902 2,501,794 Stephens Mar. 28, 19502,962,110 Depman Nov. 29, 1960

1. MEANS FOR CONNECTING A PULSATION ABSORBER WITH A PORT OF APULSATION-GENERATING APPARATUS SUCH AS A RECIPROCATING COMPRESSER,COMPRISING AN OUTER PIPE (8) HAVING A REDUCED DIAMETER AT ONE ENDTHEREOF AND BEING RIGIDLY FASTENED TO AND OPENING INTO THE INTERIOR OFTHE PULSATION ABSORBER AT THE OTHER END THEREOF, A PERFORATED INNER TUBE(7) HAVING SUBSTANTIALLY THE SAME DIAMETER AS THE REDUCED DIAMETER OFSAID OUTER PIPE AND EXTENDING THROUGH SAID PIPE COAXIALLY THEREWITH ANDINTO THE INTERIOR OF THE PULSATION ABSORBER, SAID INNER TUBE AND OUTERPIPE DEFINING AN EXPANSION SPACE (9) THEREBETWEEN, AND MEANS ADAPTED TOPROXIMATELY CONNECT THE REDUCED END OF SAID PIPE WITH A PORT OF APULSATION-GENERATING APPARATUS.